Cytidine triphosphate promotes efficient ParB-dependent DNA condensation by facilitating one-dimensional spreading from parS

parS DNA sequences and the ParB CTPase. Using a combined dual optical tweezers confocal microscope, we observe the specific interaction of ParB with parS directly. Binding around parS is enhanced 4-fold by the presence of CTP or the non-hydrolysable analogue CTPγS. However, ParB proteins are also de...

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Published inbioRxiv
Main Authors Francisco De Asis Balaguer, Aicart-Ramos, Clara, Fisher, Gemma Lm, De Bragança, Sara, Pastrana, Cesar L, Dillingham, Mark S, Moreno-Herrero, Fernando
Format Paper
LanguageEnglish
Published Cold Spring Harbor Cold Spring Harbor Laboratory Press 11.02.2021
Subjects
CTP
Cytidine triphosphate
Deoxyribonucleic acid
DNA
Magnesium
Nucleotide sequence
Protein interaction
Proteins
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Summary:parS DNA sequences and the ParB CTPase. Using a combined dual optical tweezers confocal microscope, we observe the specific interaction of ParB with parS directly. Binding around parS is enhanced 4-fold by the presence of CTP or the non-hydrolysable analogue CTPγS. However, ParB proteins are also detected at a lower density in distal non-specific regions of DNA. This requires the presence of a parS loading site and is prevented by roadblocks on DNA, consistent with one dimensional diffusion by a sliding clamp. Magnetic tweezers experiments show that the spreading activity, which has an absolute requirement for CTP binding but not hydrolysis, results in the condensation of parS-containing DNA molecules at low nanomolar protein concentrations. We propose a model in which ParB-CTP-Mg2+ complexes move along DNA following loading at parS sites and protein:protein interactions result in the localised condensation of DNA within ParB networks. Competing Interest Statement The authors have declared no competing interest.
DOI:10.1101/2021.02.11.430778